1. Field of the Invention
The present invention relates to the technical fields of an optical apparatus, a lens unit, and an image capturing apparatus. More specifically, the present invention relates to a technical field that allows to proper adjustment of a correction process for image information without increasing an amount of correction data.
2. Description of Related Art
There are optical apparatuses equipped with a lens unit having an optical imaging system including a zoom lens and a focus lens etc., an imager device for converting image information captured through the optical imaging system into an electric signal, and the like. Such a type of optical apparatus is incorporated in various types of image capturing apparatuses, including not only video cameras and still cameras but also mobile phones etc.
Among these types of image capturing apparatuses, there are image capturing apparatuses having a function of detecting an amount of camera shake so as to prevent image quality from degradations caused by camera shake.
Images captured by such image capturing apparatuses may be influenced by various factors such as: an ambient brightness change, which is caused by a difference in the angle of each luminous flux incident on the optical imaging system, causing a reduction of the brightness as a distance from a read image center increases; a field distortion, which is caused by a lens shape of the optical imaging system, causing an increase in an amount of distortion as the distance from the read image center increases; and a chromatic aberration, which is caused by a difference in the refractive index of the optical imaging system depending on an incident light wavelength, causing changes in a relative position and a size of an image as the distance from the read image center increases.
Accordingly, the image capturing apparatuses are available with image correcting means that are intended to increase an image quality by making various corrections against the effects resulting from the ambient brightness change, the field distortion, the chromatic aberration, etc.
The image capturing apparatuses, which have the function for preventing the image quality from degradations caused by the camera shake as described above, typically perform the camera shake correction process by shifting an optical axis of the system such that a subject image to be imaged on an imaging field of the imager device remains still even when the camera shake changes the relative angle between the subject and the image capturing apparatus. However, because of such a shifting of the optical axis, this type of image capturing apparatuses performs corrections of the ambient brightness change, the field distortion and the chromatic aberration, etc. based on the shifted optical axis, which is apart from the read image center on the imaging field by a distance specified by the camera shake correction function.
The image capturing apparatuses are also available with a so-called electronic anti-shake function or image stabilizing function that employs an imager device having an area larger than an actually required area for image capturing to make the camera shake correction by shifting a read position of an image on the imager device when the camera shake occurs.
The image capturing apparatus having an electronic anti-shake function or image stabilizing function as described above also performs the camera shake correction by shifting the read position of the image when the camera shake changes the relative angle between the subject and the image capturing apparatus. Thus, in this type of image capturing apparatus, the ambient brightness change, the field distortion and the chromatic aberration, etc. also occurs due to the shifted optical axis position, which is apart from the read image center on the imaging field by the distance specified by the camera shake correction.
For the purpose of increasing the image quality or reducing the effect of the shifted optical axis, one type of the image capturing apparatuses of related art is provided with an anti-shake function and performs adjusting of the correction process for the ambient brightness change, for instance. More specifically, such a type of the image capturing apparatus is adapted to make an image correction by reading out correction data corresponding to an anticipated amount of camera shake based on a signal sent from camera shake detecting means at the time of driving of an image stabilizing lens, and changing an output gain with respect to the quantity of light received by each pixel in the imager device (See Japanese Patent Application Publication No. 2003-101866, for instance).